Apparatus for developing strips of photographic film

ABSTRACT

The leader of a strip of photographic film which is to advance along one or more arcuate sections of a path extending through the developing solution in a tank is first engaged by a stationary guide surface which is adjacent to the convex side of an arcuate path section and directs the front edge of the leader against the periphery of a driven guide roller which thereupon directs the leader into the nip between a pair of advancing rollers.

United States Patent Kfihler et al. [4 1 July 25, 1972 [54] APPARATUS FOR DEVELOPING Refirsnces Cited STRIPS 0F PHOTOGRAPHIC FILM UNITED STATES PATENTS 72 [memory R l am m g p i i 3,067,919 12/1962 Kunz ..95/94 X Fengler; Erwin Geyken, all of Munich, 39721310 H1963 Kunz "95/94 X Germany 3,477,357 11/1969 Snarr ..95 94 3,492,933 2/1970 -Knibiehly et a1... ..95/94 [73] Assignee: Agfa-Gevaert Aktiengesellschaft, Lever- 3,532,048 10/1970 Hope et al. ...95/94 kusen, Germany Primary Examiner-Samuel S. Matthews [22] Filed 1969 Assistant Examiner-Fred L. Braun Attorney-Michael S. Striker 21 A LN 878653 l 1 pp 57 ABSTRACT The leader of astrip of photographic film which is to advance [30} Forelgn Apphcatmn Pnomy Data along one or more arcuate sections of a path extending Nov. 22, 1968 Germany ..P 18 10 257.3 through the developing solution in a tank is first engaged y a stationary guide surface which is adjacent to the convex side [52] U 8 Cl 095/941 .95/89 A of an arcuate path section and directs the'front edge of the (503d 3/12 leader against the periphery of a driven guide roller which thereupon directs the leader into the nip between a pair of ad- [58] Field of Search ..95/89 R, 94 R, 89 A Vancing rollers.

8 Claims, 1 Drawing Figure PKTENTEDJUL 25 I972 w 5 Q i INKEN TOR. ROLAND KOHLER HANS DIETER FRICK HA GLER ER GEYKEN BY RALD FEN wm [41/411 fhll APPARATUS FOR DEVELOPING STRIPS OF PHOTOGRAPHIC FILM CROSS-REFERENCE TO RELATED APPLICATION The developing apparatus of the present invention constitutes an improvement over and a further development of apparatus disclosed in US Pat. No. 3,435,749 granted Apr. 1, 1969 to Canwe et al. and assigned to the same assignee.

BACKGROUND OF THE INVENTION The present invention relates to apparatus for treatment of photosensitive material, particularly to apparatus for developing strips or sheets of exposed photographic film. Still more particularly, the invention relates to improvements in devices which insure automatic transport of strips of exposed film or the like along a predetermined path which extends through a supply of developing solution in one or more tanks.

In presently known developing tanks wherein the film is guided along a path which includes straight and arcuate sections, the means for guiding the film to insure that it does not deviate from the prescribed path comprises stationary guide members along which the leader of the film is caused to travel in order to enter nips between successive pairs of advancing rollers. The convex side of the strip slides along such stationary guide members during transport through the developing solution in the tank whereby such sliding engagement can result in scratching or other damage to emulsion on the strip.

SUMMARY OF THE INVENTION An object of the invention is to provide an apparatus wherein strips of photographic film or the like are guided along a predetermined path having straight and/or arcuate sections and wherein the leader of each strip is automatically compelled to remain in the desired path by guide means which is designed to avoid scratching or other damage to emulsion on the strips.

Another object of the invention is to provide a developing apparatus for strips of exposed photographic film wherein damage to emulsion on such strips is avoided in a simple and inexpensive way.

A further object of the invention is to provide an apparatus wherein the leader of each strip is automatically caused to follow one or more arcuate paths and wherein the means for effecting such automatic threading of strips comprises a relatively small number of simple and inexpensive parts.

The invention is embodied in an apparatus for treating travelling sheets or strips of photosensitive material, particularly for developing strips of exposed photographic roll film. The apparatus comprises a vessel, advancing means including at least two pairs of advancing members arranged to advance the leader and thereupon successive increments of a strip in the vessel along an arcuate path having a convex side and a concave side so that successive increments of the strip advance between one of the pairs of advancing members, thereupon along the arcuate path and enter between the other pair of advancing members, and guide means for directing the leader of such strip between the advancing members of the other pair. The guide means includes at least one rotary first guide member adjacent to the convex side of the arcuate path and a second guide member adjacent to the convex side of the path and having a guide surface which directs the oncoming leader against the periphery of the first guide member, preferably against a point of the periphery which is rather close to the convex side of the path. The rotary guide member thereupon automatically directs the leader toward the nip between the guide members of the other pair. Once the leader has moved beyond the guide members of the other pair, successive increments of the strip are automatically advanced along the arcuate path and are preferably out of contact with the guide surface.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved apparatus itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain specific embodiments with reference to the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING The single FIGURE is a schematic vertical sectional view of a developing apparatus which embodies the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The drawing shows an apparatus which comprises a vessel or tank 1 containing a supply of developing solution and. accommodating two vertical platens 1a (only one shown) which support the film advancing and guiding means of the present invention. The platens 1a are secured to each other by bolts or other suitable fasteners, not shown. The advancing means comprises seven pairs of driven advancing rollers 2, 2a which are mounted on the platens 1a and are distributed in such a way that, once the leader 21 of a strip 3 has advanced beyond the rearmost pair of rollers 2, 2a, successive increments of the strip 3 advance in the tank 1 along a substantially U-shaped path including straight and/or arcuate sections. Two substantially straight sections 3A, 3B of the U-shaped path are shown between the second and third and between the fifth and sixth pairs of advancing rollers 2, 211, as considered in the direction of travel of the strip 3 (arrow A). In accordance with a feature of the invention, the apparatus further comprises five sets of novel guide means which are respectively adjacent to the convex sides of five arcuate sections 3C, 3D, 3E, 3F, 36 of the U- shaped path. Such arcuate sections develop where the lines connecting the axes of a preceding pair of rollers 2,2a and a next-following pair of rollers 2,2a are inclined with reference to each other. Since each set of guide means is at least substantially identical with the other sets, the following description will refer mainly to that set which is adjacent to the arcuate section 3C between the first and second pairs of advancing rollers 2, 2a. At least one roller of each pair of advancing rollers is biased toward the other roller by suitable resilient means in a manner known per se and not shown in the drawing. The drive means for the rollers 2, 2a comprises at least one chain 15 which is trained over sprocket wheels 16. The arrangement can be such that one roller (e.g., the roller 2) drives the other roller of the corresponding pair of advancing rollers through the intermediary of the strip 3. As shown for the fifth pair of rollers 2, 2a, a line 17 which is tangent to the adjoining portion of the strip 3 and includes the point where the roller 2a contacts the convex side of the strip 3 is at least substantially normal to the line 18 connecting the axes of such rollers.

The guide means between the first and second pairs of advancing rollers 2, 20 comprises a rotary guide member or roller 5 which is driven by the chain 15 and by a further sprocket wheel 19 (or by other drive means) to rotate at the exact peripheral speed of the rollers 2, 2a. Such guide means further comprises a second guide member 4 which is stationary and is provided with an elongated straight guide surface 4a serving to direct the leader 21 of a strip 3 against the periphery of the roller 5 so that such leader strikes against the periphery at a point 50. A line 20 (see the roller 5 at the section 3D) which includes the point 5a and is tangent to the periphery of the roller 5 makes an acute angle alpha with the adjoining portion of the arcuate path section and an acute angle beta with a line which is tangent to the roller 5 and includes the point 5b where such roller contacts the strip 3. This insures that the roller 5 automatically advances the leader 21 of the strip 3 into the nip between the next-following pair of advancing rollers 2, 2a and that the leader 21 is not caused to flex on impact against the guide roller. Thus, the leader 21 is automatically deflected toward the convex side of the arcuate path section. Once the leader 21 is moved beyond the guide roller 5, the latter contacts successive increments of the strip 3 but such increments remain spaced from the surface 44 of the fixed guide member 4. The distance between the surface 4a and the arcuate section 3D of the U-shaped path is preferably a multiple of the average thickness of a strip 3; such thickness is normally about one-tenth of a millimeter. The shortest distance between the surface 40 and the section 3C preferably equals the shortest distance between the surface 4a and the periphery of the roller 5. Such distance is preferably short; it should not exceed the length of that foremost part of the leader 21 which is not used for the application of an identifying mark or code number on the strip 3. A line 22 drawn through the point 5b where the periphery of a roller 5 (see the last roller 5) contacts successive increments of the strip 3 and tangent to the periphery of the roller 5 is also tangent to the convex side of the adjacent arcuate path section. The line 22 is preferably at least substantially parallel to the surface 4a of the adjacent fixed guide member 4.

If desired, the guide means along the section 3C may include two or more guide rollers 5 and at least one fixed guide member 4 located ahead of the foremost guide roller. For example, if the fourth pair of advancing rollers 2, 2a is omitted, the arcuate path including the sections 3D, 3E extends along a guide means having two guide rollers 5 and two fixed guide members 4.

Each fixed guide member 4 preferably consists of a sheet of rustproof elastically deformable metallic material and has a curved trailing end suspended on a supporting post 6. One of the platens la carries stop pins 7 each of which abuts against an intermediate portion of one of the guide members 4. These guide members have brackets 8 which are spot welded to the respective stop pins 7. This insures that the guide members 4 are located in optimum positions with reference to the rollers 5 and the U-shaped path.

The operation:

The rollers 2, 2a and 5 are driven by the chain or chains so that the rollers 2, 2a of each pair rotate in opposite directions and that their peripheral speed equals the peripheral speed of the rollers 5. The leader 21 of a fresh strip 3 is introduced into the nip between the foremost rollers 2, 2a in the direction indicated by arrow A whereby the front edge of the leader advances toward and engages the surface 4a of the fixed guide member 4 at the convex side of the arcuate path section 3C. The surface 4a directs the leader 21 against the point 5a on the periphery of the guide roller 5 and the latter directs the leader into the nip between the next-following rollers 2, 2a. The leader 21 is normally straight and, after it moves beyond the foremost pair of rollers 2, 2a, it travels along a path which coincides with a line including the tangent to the points where the foremost rollers 2, 2a engage the strip 3. The guide surface 4a directs the leader 21 toward the pint 5a on the guide roller 5 without any appreciable contact between the guide member 4 and the emulsion on the strip 4. If the roller 5 is not driven, it begins to rotate in automatic response to engagement with the oncoming leader 21 and such rotation results in travel of the front edge of the leader 21 toward the convex side of the arcuate path section 3C. This takes place without any slippage between the leader 21 and the periphery of the roller 5. The same procedure is repeated when the leader 21 enters the arcuate sections 3D, 3E, 3F and 3G.

The auxiliary guide members 9 which flank the substantially straight sections 3A, 3B and the concave sides of sections 3C, 3F of the U-shaped path are provided for the purpose of properly guiding leaders which exhibit a strong tendency to curl. Also, the auxiliary guide members 9 insure proper trans port of a leader when the liquid in the vessel 1 is agitated and produces strong currents which tend to move the leader away from the desired path. In normal operation, the auxiliary guide members 9 remain out of contact with the strip 3.

As explained above, the guide means along each arcuate section of the U-shaped path may include two or more rotary guide members and two or more stationary guide members, depending on the length and curvature of arcuate sections.

Moreover, each roller 2, 2a and/or 5 may comprise a series of discrete coaxial rolls which can turn on a common axis with and/or relative to each other. The strip 3 may consist of several lengths of exposed roll film which are joined end-toend. Also, the strip 3 may constitute a flexible carrier for discrete sheets of exposed photographic film. The tank 1 may constitute one of several vessels through which the strip is guided during processing, and each such vessel may contain one or more sets of improved guide means.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features which fairly constitute essential characteristics of the generic and specific aspects of our contribution to the art.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims:

1. In an apparatus for treating travelling photosensitive material, particularly for developing strips including exposed photographic film, a combination comprising a vessel; advancing means including at least two pairs of advancing rollers rotatable in opposite directions and arranged to advance the leader and thereupon successive increments of a strip in the vessel along an arcuate path having a convex side and a concave side so that successive increments of the strip advance between one of said pairs of advancing rollers, thereupon along said arcuate path and enter between the advancing rollers of the other pair; guide means for directing the leader of such strip between the advancing rollers of said other pair, including at least one rotary first guide member adjacent to the convex side of said arcuate path ahead of the advancing rollers of said other pair and a second guide member adjacent to said convex side between said one pair of advancing rollers and said first guide member and having a guide surface for directing the oncoming leader against the periphery of said first guide member, said first guide member being positioned to thereupon direct the leader between the advancing rollers of said other pair and to maintain the strip out of contact with said guide surface of said second guide member; and drive means for rotating at least one roller of each pair of advancing rollers and said first guide member at a predetermined peripheral speed.

2. A combination as defined in claim 1, wherein the periphery of said first guide member contacts the strip travelling along said path at a predetermined point and wherein a line including said point and tangent to the convex side of said arcuate path is also tangent to the periphery of said first guide member.

3. A combination as defined in claim 1, wherein said guide surface is spaced from the convex side of said arcuate path by a distance which is a multiple of the average thickness of a strip.

4. A combination as defined in claim 1, wherein said guide surface is spaced from said periphery and from said convex side and wherein the minimum distance between said surface and said periphery at least approximates the minimum distance between said surface and said convex side.

5. A combination as defined in claim 1, wherein the guide surface of said second guide member is positioned to direct the leader of the strip against a predetermined point on the periphery of said first guide member and wherein a line including said point and tangent to said periphery makes an acute angle with the adjacent portion of said path.

6. A combination as defined in claim 1, wherein said second guide member is elastic.

7. A combination as defined in claim 1, wherein said advancing means includes more than two pairs of advancing rollers arranged to advance strip along a substantially U-shaped path including a plurality of arcuate paths.

8. A combination as defined in claim 1, wherein said guide surface of said second guide member is an elongated flat surface and the periphery of said first guide member contacts the strip travelling along said arcuate path at a predetermined point, a line including said predetermined point and tangent to said convex side of said path being also tangent to the periphery of said first guide member and substantially parallel to said flat surface. 

1. In an apparatus for treating travelling photosensitive material, particularly for developing strips including exposed photographic film, a combination comprising a vessel; advancing means including at least two pairs of advancing rollers rotatable in opposite directions and arranged to advance the leader and thereupon successive increments of a strip in the vessel along an arcuate path having a convex side and a concave side so that successive increments of the strip advance between one of said pairs of advancing rollers, thereupon along said arcuate path and enter between the advancing rollers of the other pair; guide means for directing the leader of such strip between the advancing rollers of said other pair, including at least one rotary first guide member adjacent to the convex side of said arcuate path ahead of the advancing rollers of said other pair and a second guide member adjacent to said convex side between said one pair of advancing rollers and said first guide member and having a guide surface for directing the oncoming leader against the periphery of said first guide member, said first guide member being positioned to thereupon direct the leader between the advancing rollers of said other pair and to maintain the strip out of contact with said guide surface of said second guide member; and Drive means for rotating at least one roller of each pair of advancing rollers and said first guide member at a predetermined peripheral speed.
 2. A combination as defined in claim 1, wherein the periphery of said first guide member contacts the strip travelling along said path at a predetermined point and wherein a line including said point and tangent to the convex side of said arcuate path is also tangent to the periphery of said first guide member.
 3. A combination as defined in claim 1, wherein said guide surface is spaced from the convex side of said arcuate path by a distance which is a multiple of the average thickness of a strip.
 4. A combination as defined in claim 1, wherein said guide surface is spaced from said periphery and from said convex side and wherein the minimum distance between said surface and said periphery at least approximates the minimum distance between said surface and said convex side.
 5. A combination as defined in claim 1, wherein the guide surface of said second guide member is positioned to direct the leader of the strip against a predetermined point on the periphery of said first guide member and wherein a line including said point and tangent to said periphery makes an acute angle with the adjacent portion of said path.
 6. A combination as defined in claim 1, wherein said second guide member is elastic.
 7. A combination as defined in claim 1, wherein said advancing means includes more than two pairs of advancing rollers arranged to advance strip along a substantially U-shaped path including a plurality of arcuate paths.
 8. A combination as defined in claim 1, wherein said guide surface of said second guide member is an elongated flat surface and the periphery of said first guide member contacts the strip travelling along said arcuate path at a predetermined point, a line including said predetermined point and tangent to said convex side of said path being also tangent to the periphery of said first guide member and substantially parallel to said flat surface. 